Feat: Add support for multiple log panes

[silopolis]

Of course, as a MultiTail fan and longtime user, I couldn't refrain asking for this one.

In many situations having the possibility to tail and filter several journals/logs/files/pipes is essential.

[Lifailon]

@silopolis do you need to be able to simultaneously display the contents of several magazines in different panels (for example, two, and not the fixed one panel that is now)?

[Lifailon]

@silopolis Please clarify in more detail how exactly you see this process? I will consider this functionality in future releases